The objective of the proposed research is to evaluate the effect of selected hard coatings on the cutting performance (cutting ability and durability) of tungsten carbide dental burs. Six hard coating materials (LaB6, SiC, TiB2, A1B12, WB and B4C) will be deposited by RF sputtering in three thicknesses (5, 15 and 25 micrometers) on commercial FG 57 carbide burs. These burs will then be subjected to a standard performance test involving milling float glass specimens. The initial cutting rate and distance cut before cessation of cutting will be used to define two performance parameters, cutting ability and durability. The optimum cutting ability-durability product will be used to define the best coating material, thickness, and deposition parameter combination for optimized performance. This optimized coating will then be applied to several different brands of FG 57 bur to determine the range of (presumed) performance improvement to be expected in hard coated burs.